The recent rapid development of receiver technology has allowed the construction of multi-element heterodyne arrays at FIR frequencies. In particular, the upGREAT instrument has been specifically designed to map the [C ii] \(158\,\mu \mathrm {m}\)  line [1]}. This sensitive instrument coupled with the nimble telescope of the Stratospheric Observatory For Infrared Astronomy (SOFIA) allows for the first time wide-field [C ii] observations of regions of massive star formation at sub-km s\(^{-1}\)  spectral resolution [2]}, [3]}. The C+SQUAD SOFIA Large Program has surveyed one square degree of the molecular cloud cores in Orion in the [C ii] \(158\,\mu \mathrm {m}\)  line to probe the radiative and mechanical energy feedback of massive stars with their environment. The results revealed the presence of a \(\sim 2\)  pc radius massive (\(\sim 1500\,M_{\odot }\) ) shell of neutral atomic gas expanding at 13 km s\(^{-1}\)  [4]}. The rapid expansion of this bubble is driven by the hot plasma generated by the stellar wind from the O7V star \(\theta ^1\)  Ori C [5]} as envisioned by [6]}. The data also revealed bubbles of neutral gas expanding at a slower pace around the B1 stars powering the H ii regions M43 and NGC 1977 [7]}. In this case, expansion is driven by the overpressure of the ionized gas, a so-called Spitzer expansion. While these studies focused on the kinematics of the region and the mechanical feedback by massive stars, this data also allows an in depth study of the radiative interaction of massive stars with neutral atomic gas on unprecedented spatial scales.
